Digital RF transmitter design

• Main Author: Cheng, Deruo
• Other Authors: Gwee Bah Hwee
• Format: Final Year Project
• Language: English
• Published: 2016
• Subjects: DRNTU::Engineering
• Online Access: http://hdl.handle.net/10356/67912
• Institution: Nanyang Technological University

This Final Year Project is aimed to design a digital RF transmitter with proposed new architecture. Conventional quadrature and polar transmitters are firstly designed to function as a reference, followed by the design of the proposed digital polar transmitter. Mathematic expressions for various modulations schemes are derived. Models are built respectively to obtain good understanding of different modulation features. Based on the comparison between different modulation schemes and transmitter architectures, the proposed transmitter architecture is decided. Conventional quadrature transmitter and polar transmitter are modeled based on the quadrature expression and polar expression of the generalized modulated signal. The simulation result shows these two transmitter designs have nearly identical signal waveforms and power spectrum density. The digital polar transmitter design separates the amplitude and phase information of the baseband signal. The amplitude information is modulated into a 1-bit digital data through a 1st order ∆∑ modulator. The phase information is modulated onto the digital carrier through variable time delay. The modulated amplitude information and phase information are mixed to produce the output modulated signal. After bandpass filtering, the output signal is proved to have a 20dB noise floor, which meets the requirement of subsequent SMPA (switch mode power amplifier).